The Neglect of Cliemistry by Practical Farmers. 



425 



added together, equal in amount the weight of the original 

 specimen. 



Organic, or Comhustihle Matter — Ultimate and Proximate 

 Elements. — Having in the preceding paragraph explained the mean- 

 ins: of the term organic matter, we now come to consider of what 

 it is composed. Chemists have two different modes of recording 

 the results of their analyses, the one giving the ultimate elements, 

 and the other the different forms in which these ultimate elements 

 are combined in the matter analysed. 



Ultimate Elements. — Ultimate elements are those simple sub- 

 stances which are not susceptible of any further decomposition, 

 and in all organic matter they consist of carbon, hydrogen, oxygen, 

 and nitrogen. 



Carbon. — Pure carbon is found in its solid state only in the 

 diamond, which is entirely composed of crystallized carbon. 

 Common charcoal is principally composed of carbon, and for all 

 practical purposes may be considered as identical with it, though 

 it has generally a varying amount of hydrogen and oxygen in 

 union with it, in addition to its mineral ash. The form in which 

 it is assimilated by plants is probably that of carbonic acid, being 

 a union of carbon and oxygen (existing, when uncombined with 

 other substances, in the form of a gas). This gas is the bad air 

 we exhale from our lungs, and is identical with that which 

 collects in mines, wells, &c., and so often occasions fatal accidents 

 on account of its not being either a supporter of life or combus- 

 tion. It is also found in soda-water and all other effervescing 

 and fermentins: beverag-es. 



Hydrogen. — This element, when uncombined, exists in the 

 form of a gas, and is used for the inflation of balloons, being the 

 lightest substance known. In union with oxygen, in the propor- 

 tion of 1 to 8 by weight, it forms water ; in combination with 

 carbon it forms the highly explosive gas so much dreaded in 

 mines, called fire-damp, and the common coal gas, with which the 

 streets are lighted. 



Oxygen. — This element, whose natural state, when uncombined, 

 is also that of a gas, is the chief supporter of life and combustion. 

 In mechanical mixture with nitrogen, in the proportion of 8 

 oxygen to 28 nitrogen by weight, it forms the common air we 

 breathe, and in chemical combination with hydrogen, as previously 

 stated — water. No animal, plant, or flame can exist without it. 



Nitrogen. — Nitrogen, or azote, is chiefly distinguished by 

 negative qualities, such as being incapable of supporting either 

 combustion or animal life ; its use in common air appears to be 

 to dilute the powerful effects of the oxygen gas. In an agricul- 

 tural point of view, this may be considered the most important of 

 the organic gases. 



2 F 2 



